The stress response saves your life in an emergency. It turns harmful when it never shuts off. Chronic stress keeps cortisol and the sympathetic nervous system switched on. The neuroscientist Robert Sapolsky made this point in his book Why Zebras Don’t Get Ulcers. The same system that helps a zebra outrun a lion slowly wears down a person who is stressed for months. Pick how long the stress lasts, then tap each body system to see what happens to it.
A body under chronic stress
Tap a marker, or a system in the list, to see the effect. One driver, seven targets.
The body under chronic stresspick a time span, then tap a system
How long has the stress lasted?
Wear and tear (allostatic load): high
One switch, many targetsShort-term stress is helpful. It is a burst of energy that helps you cope and then fades. The damage comes from chronic stress. The HPA axis and the sympathetic nervous system stay on for weeks or months. High cortisol then reaches nearly every organ. Tap a system to see what happens to it.
HPA axis:Hypothalamus → Pituitary (ACTH) → Adrenal cortex → cortisol. The adrenal medulla adds the fast hit: epinephrine and norepinephrine. In an emergency this saves lives. Left on for months, it wears the body down.
Allostatic load: The scientist Bruce McEwen gave this name to the built-up "wear and tear" from a stress response that never resets. Earlier, Hans Selye called the illnesses that follow the diseases of adaptation. Much of the harm eases once the stressor ends. The body wants to recover.